1. Field of the Invention
The instant disclosure relates to a common mode filter; in particular, to a thin-film common mode filter for a portable electric device.
2. Description of Related Art
Common mode filter is a component used to suppress common mode current that causes electromagnetic interference (EMI) conducted on parallel lines in the same direction as a source of the noise in electronic circuit. To address the miniaturizing requirement of portable electronic apparatuses, thin-film common mode filters have been developed.
Japanese Patent Application Laid-Open NO. 2000-173824A discloses one type of electronic component, which includes an insulating substrate, a multi-layer structure, and a plurality of external electrode terminals. The multi-layer structure is arranged on the insulating substrate and comprises a plurality of conducting patterns and a plurality of insulating layers, wherein two of the conducting patterns are laminated with one insulating layer interposed therebetween for electrically insulating the conducting patterns. The external electrode terminals are surroundingly arranged on the insulating substrate and the multi-layer structure for establishing an external electrical connection. Moreover, the electronic component further comprises a plurality of magnetic layer or sheet to cover at least part of the conducting patterns.
For such structural design, the electronic component needs to modify the conducting patterns of the multi-layer structure to adjust the common mode impedance. However, more improvements may cause the large volume of the electronic component and affect the process variables due to the complex structure of the electronic component.
To address the above issues, the inventors strive via industrial experience and academic research to present the instant disclosure, which can effectively improve the limitations described above.